1. Field of the Invention
The present invention relates to a process for producing methyl methacrylate from acetone and methyl formate, or from acetone, methanol and carbon monoxide as starting materials.
A large amount of methyl methacrylate is used as a starting material for production of various polymers, and the methyl methacrylate is a greatly important intermediate in industrial use.
2. Description of Related Arts
A process for producing methyl methacrylate in which acetonecyanhydrin is prepared from acetone and prussic acid, .alpha.-hydroxyisobutyric acid amide is prepared from the acetonecyanhydrin in the presence of sulfuric acid, and then methyl methacrylate is prepared using methacrylamide derived from the .alpha.-hydroxyisobutyric acid amide is well known, as described in, for example, Kirk Othmer "Encyclopedia of Chemical Technology", 3rd ed., Vol. 15, p. 357. This process is widely carried out on a commercial scale.
The conventional process, however, has disadvantages in that large amounts of waste sulfuric acid and acidic ammonium sulfate are by-produced and the treatment thereof increases production costs of methyl methacrylate.
Heretofore, the acidic ammonium sulfate has been converted into ammonium sulfate as a fertilizer by addition of ammonia. Presently, however, a demand for the ammonium sulfate fertilizer is limited. For this reason, in recent years, a method of recovering sulfuric acid by decomposition of acidic ammonium sulfate has been put to practical use. This method, however, increases production costs and furthermore, since the nitrogen is insufficiently recovered, it is not a very economical process.
In order to overcome the problems as described above, the present inventors have proposed a method of preparation of methyl methacrylate without use of sulfuric acid according to the route shown by the reaction equation (I), in Japanese Patent Application Laid-Open No. 78939/1985. ##STR1##
In the above equation, ACH represents acetonecyanhydrin; HBD, .alpha.-hydroxyisobutyric acid amide; HBM, methyl .alpha.-hydroxyisobutyrate; FD, formamide; and MMA, methyl methacrylate (same also in the equation (II)).